Rebel is held by soldiers (4)
I believe the answer is:
rise
'rebel' is the definition.
(I know that rebel can be written as rise)
'is held by soldiers' is the wordplay.
'held by' means one lot of letters goes inside another.
'soldiers' becomes 're' (Royal Engineers).
'is' going inside 're' is 'RISE'.
(Other definitions for rise that I've seen before include "Get or stand up" , "hike" , "Pay increase" , "Ascent" , "Provide (an opportunity)" .)